The activation of NLRP3-inflammsome by stimulation of diesel exhaust particles in lung tissues from emphysema model and RAW 264.7 cell line

Korean J Intern Med. 2017 Sep;32(5):865-874. doi: 10.3904/kjim.2016.033. Epub 2017 Aug 18.

Abstract

Background/aims: Diesel exhaust particles (DEPs) lead to elevation of reactive oxygen species, which can activate the nucleotide-binding oligomerization domain-like receptor (NLR) family members containing the pyrin domain 3 (NLRP3)-inf lammasome. In this study, we elucidated whether NLRP3 -inf lammasome is activated by DEPs and whether antioxidants (N-acetylcysteine [NAC]) could inhibit such activation.

Methods: RAW 264.7 cells and ex vivo lung tissues explants obtained from elastase-induced emphysema animal models were stimulated with cigarette smoking extract (CSE), DEPs, and lipopolysaccharide, and levels of interleukin-1β (IL-1β), caspase-1 and nucleotide-binding oligomerization domain-like receptor (NLR) family members containing the pyrin domain (NLRP3)-inflammasome were assessed by Western blotting and immunohistochemistry.

Results: NAC and caspase-1 inhibitor suppressed CSE- and DEP-induced secretion of IL-1β in RAW 264.7 cells. The expression levels of the NLRP3-inflammasome and caspase-1 were upregulated in RAW 264.7 cells by stimulation with CSE and DEPs and were inhibited by NAC. CSE and DEPs increased the secretion of IL-1β in lung tissues from both the normal and elastase-induced emphysema groups. The secretion of IL-1β by CSE and DEPs was increased in the elastin-induced emphysema group more than that in the normal group (CSE: 309 ± 19 pg/mL vs. 151 ± 13 pg/mL, respectively, p < 0.05; DEP: 350 ± 24 pg/mL vs. 281 ± 15 pg/mL, respectively, p < 0.05). NAC inhibited CSE- and DEP-induced IL-1β secretion in both the normal and elastase-induced emphysema groups. NLRP3-inflammasome expression as determined by immunohistochemistry was increased by CSE and DEPs in both the normal and elastin-induced emphysema groups, and was suppressed by NAC.

Conclusions: The NLRP3-inf lammasome is activated by DEPs in ex vivo tissue explants from elastase-induced emphysema animal model, and this activation is inhibited by NAC.

Keywords: Emphysema; Inf lammasomes; Pancreatic elastase; Pulmonary disease, chronic obstructive; Vehicle emissions.

MeSH terms

  • Acetylcysteine / pharmacology
  • Animals
  • Antioxidants / pharmacology
  • Caspase 1 / metabolism
  • Cigarette Smoking / adverse effects
  • Disease Models, Animal
  • Female
  • Inflammasomes / drug effects
  • Inflammasomes / immunology
  • Inflammasomes / metabolism*
  • Interleukin-1beta / metabolism
  • Lung / drug effects
  • Lung / immunology
  • Lung / metabolism*
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • NLR Family, Pyrin Domain-Containing 3 Protein / immunology
  • NLR Family, Pyrin Domain-Containing 3 Protein / metabolism*
  • Pancreatic Elastase
  • Particulate Matter*
  • Pulmonary Emphysema / chemically induced
  • Pulmonary Emphysema / immunology
  • Pulmonary Emphysema / metabolism*
  • Pulmonary Emphysema / prevention & control
  • RAW 264.7 Cells
  • Signal Transduction
  • Time Factors
  • Vehicle Emissions*

Substances

  • Antioxidants
  • IL1B protein, mouse
  • Inflammasomes
  • Interleukin-1beta
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, mouse
  • Particulate Matter
  • Vehicle Emissions
  • Pancreatic Elastase
  • Caspase 1
  • Acetylcysteine